diff --git a/aria/orchestrator/workflows/core/engine.py b/aria/orchestrator/workflows/core/engine.py
index fd0dd6d..561265c 100644
--- a/aria/orchestrator/workflows/core/engine.py
+++ b/aria/orchestrator/workflows/core/engine.py
@@ -42,10 +42,9 @@
         super(Engine, self).__init__(**kwargs)
         self._workflow_context = workflow_context
         self._execution_graph = networkx.DiGraph()
-        self._executor = executor
         translation.build_execution_graph(task_graph=tasks_graph,
                                           execution_graph=self._execution_graph,
-                                          default_executor=self._executor)
+                                          default_executor=executor)
 
     def execute(self):
         """
diff --git a/tests/helpers.py b/tests/helpers.py
index 423e63f..3c3efc9 100644
--- a/tests/helpers.py
+++ b/tests/helpers.py
@@ -14,7 +14,6 @@
 # limitations under the License.
 
 import os
-import tempfile
 import json
 
 from . import ROOT_DIR
@@ -34,16 +33,19 @@
 
 
 class FilesystemDataHolder(object):
-    _tmpfile = tempfile.NamedTemporaryFile('w')
+
+    def __init__(self, path, reset=False):
+        self._path = path
+        if reset or not os.path.exists(self._path) or open(self._path).read() == '':
+            self._dump({})
 
     def _load(self):
-        return json.load(open(self._tmpfile.name))
+        with open(self._path) as f:
+            return json.load(f)
 
     def _dump(self, value):
-        return json.dump(value, open(self._tmpfile.name, 'w'))
-
-    def __init__(self):
-        self.clear()
+        with open(self._path, 'w') as f:
+            return json.dump(value, f)
 
     def __setitem__(self, key, value):
         dict_ = self._load()
@@ -56,9 +58,6 @@
     def __iter__(self):
         return iter(self._load())
 
-    def clear(self):
-        self._dump({})
-
     def get(self, item, default=None):
         return self._load().get(item, default)
 
@@ -67,3 +66,7 @@
         return_value = dict_.setdefault(key, value)
         self._dump(dict_)
         return return_value
+
+    @property
+    def path(self):
+        return self._path
diff --git a/tests/orchestrator/context/test_operation.py b/tests/orchestrator/context/test_operation.py
index 3180d89..cdeb5fa 100644
--- a/tests/orchestrator/context/test_operation.py
+++ b/tests/orchestrator/context/test_operation.py
@@ -38,7 +38,6 @@
     execute,
 )
 
-global_test_holder = helpers.FilesystemDataHolder()
 
 @pytest.fixture
 def ctx(tmpdir):
@@ -68,11 +67,18 @@
         ex.close()
 
 
-def test_node_operation_task_execution(ctx, thread_executor):
+@pytest.fixture
+def dataholder(tmpdir):
+    dataholder_path = str(tmpdir.join('dataholder'))
+    holder = helpers.FilesystemDataHolder(dataholder_path)
+    return holder
+
+
+def test_node_operation_task_execution(ctx, thread_executor, dataholder):
     interface_name = 'Standard'
     operation_name = 'create'
 
-    inputs = {'putput': True}
+    inputs = {'putput': True, 'holder_path': dataholder.path}
     node = ctx.model.node.get_by_name(mock.models.DEPENDENCY_NODE_NAME)
     interface = mock.models.create_interface(
         node.service,
@@ -97,11 +103,11 @@
 
     execute(workflow_func=basic_workflow, workflow_context=ctx, executor=thread_executor)
 
-    assert global_test_holder['ctx_name'] == context.operation.NodeOperationContext.__name__
+    assert dataholder['ctx_name'] == context.operation.NodeOperationContext.__name__
 
     # Task bases assertions
-    assert global_test_holder['actor_name'] == node.name
-    assert global_test_holder['task_name'] == api.task.OperationTask.NAME_FORMAT.format(
+    assert dataholder['actor_name'] == node.name
+    assert dataholder['task_name'] == api.task.OperationTask.NAME_FORMAT.format(
         type='node',
         name=node.name,
         interface=interface_name,
@@ -109,19 +115,19 @@
     )
     operations = interface.operations
     assert len(operations) == 1
-    assert global_test_holder['implementation'] == operations.values()[0].implementation             # pylint: disable=no-member
-    assert global_test_holder['inputs']['putput'] is True
+    assert dataholder['implementation'] == operations.values()[0].implementation             # pylint: disable=no-member
+    assert dataholder['inputs']['putput'] is True
 
     # Context based attributes (sugaring)
-    assert global_test_holder['template_name'] == node.node_template.name
-    assert global_test_holder['node_name'] == node.name
+    assert dataholder['template_name'] == node.node_template.name
+    assert dataholder['node_name'] == node.name
 
 
-def test_relationship_operation_task_execution(ctx, thread_executor):
+def test_relationship_operation_task_execution(ctx, thread_executor, dataholder):
     interface_name = 'Configure'
     operation_name = 'post_configure'
 
-    inputs = {'putput': True}
+    inputs = {'putput': True, 'holder_path': dataholder.path}
     relationship = ctx.model.relationship.list()[0]
     interface = mock.models.create_interface(
         relationship.source_node.service,
@@ -148,14 +154,14 @@
 
     execute(workflow_func=basic_workflow, workflow_context=ctx, executor=thread_executor)
 
-    assert global_test_holder['ctx_name'] == context.operation.RelationshipOperationContext.__name__
+    assert dataholder['ctx_name'] == context.operation.RelationshipOperationContext.__name__
 
     # Task bases assertions
-    assert global_test_holder['actor_name'] == relationship.name
-    assert interface_name in global_test_holder['task_name']
+    assert dataholder['actor_name'] == relationship.name
+    assert interface_name in dataholder['task_name']
     operations = interface.operations
-    assert global_test_holder['implementation'] == operations.values()[0].implementation           # pylint: disable=no-member
-    assert global_test_holder['inputs']['putput'] is True
+    assert dataholder['implementation'] == operations.values()[0].implementation           # pylint: disable=no-member
+    assert dataholder['inputs']['putput'] is True
 
     # Context based attributes (sugaring)
     dependency_node_template = ctx.model.node_template.get_by_name(
@@ -165,14 +171,14 @@
         mock.models.DEPENDENT_NODE_TEMPLATE_NAME)
     dependent_node = ctx.model.node.get_by_name(mock.models.DEPENDENT_NODE_NAME)
 
-    assert global_test_holder['target_node_template_name'] == dependency_node_template.name
-    assert global_test_holder['target_node_name'] == dependency_node.name
-    assert global_test_holder['relationship_name'] == relationship.name
-    assert global_test_holder['source_node_template_name'] == dependent_node_template.name
-    assert global_test_holder['source_node_name'] == dependent_node.name
+    assert dataholder['target_node_template_name'] == dependency_node_template.name
+    assert dataholder['target_node_name'] == dependency_node.name
+    assert dataholder['relationship_name'] == relationship.name
+    assert dataholder['source_node_template_name'] == dependent_node_template.name
+    assert dataholder['source_node_name'] == dependent_node.name
 
 
-def test_invalid_task_operation_id(ctx, thread_executor):
+def test_invalid_task_operation_id(ctx, thread_executor, dataholder):
     """
     Checks that the right id is used. The task created with id == 1, thus running the task on
     node with id == 2. will check that indeed the node uses the correct id.
@@ -191,7 +197,8 @@
         node.service,
         interface_name=interface_name,
         operation_name=operation_name,
-        operation_kwargs=dict(implementation=op_path(get_node_id, module_path=__name__))
+        operation_kwargs=dict(implementation=op_path(get_node_id, module_path=__name__),
+                              inputs={'holder_path': dataholder.path})
     )
     node.interfaces[interface.name] = interface
     ctx.model.node.update(node)
@@ -202,12 +209,13 @@
             api.task.OperationTask(
                 node,
                 interface_name=interface_name,
-                operation_name=operation_name)
+                operation_name=operation_name,
+            )
         )
 
     execute(workflow_func=basic_workflow, workflow_context=ctx, executor=thread_executor)
 
-    op_node_id = global_test_holder[api.task.OperationTask.NAME_FORMAT.format(
+    op_node_id = dataholder[api.task.OperationTask.NAME_FORMAT.format(
         type='node',
         name=node.name,
         interface=interface_name,
@@ -376,42 +384,41 @@
 
 
 @operation
-def basic_node_operation(ctx, **_):
-    operation_common(ctx)
-    global_test_holder['template_name'] = ctx.node_template.name
-    global_test_holder['node_name'] = ctx.node.name
+def basic_node_operation(ctx, holder_path, **_):
+    holder = helpers.FilesystemDataHolder(holder_path)
+
+    operation_common(ctx, holder)
+    holder['template_name'] = ctx.node_template.name
+    holder['node_name'] = ctx.node.name
 
 
 @operation
-def basic_relationship_operation(ctx, **_):
-    operation_common(ctx)
-    global_test_holder['target_node_template_name'] = ctx.target_node_template.name
-    global_test_holder['target_node_name'] = ctx.target_node.name
-    global_test_holder['relationship_name'] = ctx.relationship.name
-    global_test_holder['source_node_template_name'] = ctx.source_node_template.name
-    global_test_holder['source_node_name'] = ctx.source_node.name
+def basic_relationship_operation(ctx, holder_path, **_):
+    holder = helpers.FilesystemDataHolder(holder_path)
+
+    operation_common(ctx, holder)
+    holder['target_node_template_name'] = ctx.target_node_template.name
+    holder['target_node_name'] = ctx.target_node.name
+    holder['relationship_name'] = ctx.relationship.name
+    holder['source_node_template_name'] = ctx.source_node_template.name
+    holder['source_node_name'] = ctx.source_node.name
 
 
-def operation_common(ctx):
-    global_test_holder['ctx_name'] = ctx.__class__.__name__
+def operation_common(ctx, holder):
+    holder['ctx_name'] = ctx.__class__.__name__
 
-    global_test_holder['actor_name'] = ctx.task.actor.name
-    global_test_holder['task_name'] = ctx.task.name
-    global_test_holder['implementation'] = ctx.task.implementation
-    global_test_holder['inputs'] = dict(i.unwrap() for i in ctx.task.inputs.values())
+    holder['actor_name'] = ctx.task.actor.name
+    holder['task_name'] = ctx.task.name
+    holder['implementation'] = ctx.task.implementation
+    holder['inputs'] = dict(i.unwrap() for i in ctx.task.inputs.values())
 
 
 @operation
-def get_node_id(ctx, **_):
-    global_test_holder[ctx.name] = ctx.node.id
+def get_node_id(ctx, holder_path, **_):
+    helpers.FilesystemDataHolder(holder_path)[ctx.name] = ctx.node.id
 
 
 @operation
 def _test_plugin_workdir(ctx, filename, content):
     with open(os.path.join(ctx.plugin_workdir, filename), 'w') as f:
         f.write(content)
-
-
-@pytest.fixture(autouse=True)
-def cleanup():
-    global_test_holder.clear()
diff --git a/tests/orchestrator/context/test_toolbelt.py b/tests/orchestrator/context/test_toolbelt.py
index 822ac5a..d199954 100644
--- a/tests/orchestrator/context/test_toolbelt.py
+++ b/tests/orchestrator/context/test_toolbelt.py
@@ -30,12 +30,10 @@
     execute,
 )
 
-global_test_holder = helpers.FilesystemDataHolder()
-
 
 @pytest.fixture
 def workflow_context(tmpdir):
-    context = mock.context.simple(str(tmpdir), inmemory=True)
+    context = mock.context.simple(str(tmpdir))
     yield context
     storage.release_sqlite_storage(context.model)
 
@@ -49,6 +47,13 @@
         result.close()
 
 
+@pytest.fixture
+def dataholder(tmpdir):
+    dataholder_path = str(tmpdir.join('dataholder'))
+    holder = helpers.FilesystemDataHolder(dataholder_path)
+    return holder
+
+
 def _get_elements(workflow_context):
     dependency_node_template = workflow_context.model.node_template.get_by_name(
         mock.models.DEPENDENCY_NODE_TEMPLATE_NAME)
@@ -75,17 +80,17 @@
         relationship
 
 
-def test_host_ip(workflow_context, executor):
+def test_host_ip(workflow_context, executor, dataholder):
+
     interface_name = 'Standard'
     operation_name = 'create'
     _, dependency_node, _, _, _ = _get_elements(workflow_context)
-    inputs = {'putput': True}
+    inputs = {'putput': True, 'holder_path': dataholder.path}
     interface = mock.models.create_interface(
         dependency_node.service,
         interface_name=interface_name,
         operation_name=operation_name,
-        operation_kwargs=dict(implementation=op_path(host_ip, module_path=__name__),
-                              inputs=inputs)
+        operation_kwargs=dict(implementation=op_path(host_ip, module_path=__name__), inputs=inputs)
     )
     dependency_node.interfaces[interface.name] = interface
     dependency_node.runtime_properties['ip'] = '1.1.1.1'
@@ -105,14 +110,14 @@
 
     execute(workflow_func=basic_workflow, workflow_context=workflow_context, executor=executor)
 
-    assert global_test_holder.get('host_ip') == dependency_node.runtime_properties.get('ip')
+    assert dataholder.get('host_ip') == dependency_node.runtime_properties.get('ip')
 
 
-def test_relationship_tool_belt(workflow_context, executor):
+def test_relationship_tool_belt(workflow_context, executor, dataholder):
     interface_name = 'Configure'
     operation_name = 'post_configure'
     _, _, _, _, relationship = _get_elements(workflow_context)
-    inputs = {'putput': True}
+    inputs = {'putput': True, 'holder_path': dataholder.path}
     interface = mock.models.create_interface(
         relationship.source_node.service,
         interface_name=interface_name,
@@ -136,7 +141,7 @@
 
     execute(workflow_func=basic_workflow, workflow_context=workflow_context, executor=executor)
 
-    assert global_test_holder.get(api.task.OperationTask.NAME_FORMAT.format(
+    assert dataholder.get(api.task.OperationTask.NAME_FORMAT.format(
         type='relationship',
         name=relationship.name,
         interface=interface_name,
@@ -149,15 +154,10 @@
 
 
 @operation(toolbelt=True)
-def host_ip(toolbelt, **_):
-    global_test_holder['host_ip'] = toolbelt.host_ip
+def host_ip(toolbelt, holder_path, **_):
+    helpers.FilesystemDataHolder(holder_path)['host_ip'] = toolbelt.host_ip
 
 
 @operation(toolbelt=True)
-def relationship_operation(ctx, toolbelt, **_):
-    global_test_holder[ctx.name] = toolbelt._op_context.source_node.name
-
-
-@pytest.fixture(autouse=True)
-def cleanup():
-    global_test_holder.clear()
+def relationship_operation(ctx, toolbelt, holder_path, **_):
+    helpers.FilesystemDataHolder(holder_path)[ctx.name] = toolbelt._op_context.source_node.name
diff --git a/tests/storage/__init__.py b/tests/storage/__init__.py
index 66424db..8ca1480 100644
--- a/tests/storage/__init__.py
+++ b/tests/storage/__init__.py
@@ -51,6 +51,5 @@
 
     engine = create_engine(uri, **engine_kwargs)
     session_factory = orm.sessionmaker(bind=engine)
-    session = orm.scoped_session(session_factory=session_factory)
 
-    return dict(engine=engine, session=session)
+    return dict(engine=engine, session=session_factory())